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From:   =?Windows-1252?Q?Alvin_=8Aipraga?= <ALSI@bang-olufsen.dk>
To:     James Prestwood <prestwoj@gmail.com>
CC:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: [PATCH] brcmfmac: include missing AP scan feature
Thread-Topic: [PATCH] brcmfmac: include missing AP scan feature
Thread-Index: AQHYKas3uPpI3oxfi0CdVC9vzqacgw==
Date:   Fri, 25 Feb 2022 22:55:21 +0000
Message-ID: <87o82ud09z.fsf@bang-olufsen.dk>
References: <20220224181809.2808754-1-prestwoj@gmail.com>
In-Reply-To: <20220224181809.2808754-1-prestwoj@gmail.com> (James Prestwood's
        message of "Thu, 24 Feb 2022 10:18:09 -0800")
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Hi James,

James Prestwood <prestwoj@gmail.com> writes:

> This driver does not advertise this feature yet scanning with on an
> AP interface appears to work just fine.
> ---
>  drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> I've submitted this patch mainly to start a discussion about it. I
> find it hard to believe that ALL brcmfmac devices support AP scanning
> in which case this feature needs to be limited to those devices
> only. Trouble is there is no FW feature for AP scanning AFAIK.
>
> In any case I think this driver needs to sort out if it supports this
> feature or not, and advertise as such rather than leaving userspace
> in the dark.

By the way, what are the typical use-cases for AP scanning?

I know that hostapd does a passive scan on the AP interface on the
assumption that the driver/firmware will gather channel survey data, but
that's not a universally applicable assumption. Not all implementations
will do that.

Kind regards,
Alvin

>
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c =
b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> index fb727778312c..b6a50e65dbf6 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> @@ -7729,6 +7729,8 @@ struct brcmf_cfg80211_info *brcmf_cfg80211_attach(s=
truct brcmf_pub *drvr,
>  #endif
>  	}
> =20
> +	wiphy->features |=3D NL80211_FEATURE_AP_SCAN;
> +
>  	return cfg;
> =20
>  detach:=